Thread break detector



J. w. HARVEY, JR

"THREAD BREAK DETECTOR April 9, 1963 Filed May 16, 1962 INVENTOR BY M W ATTORNEY Edited rates l stens Biddddhd Patented Apr. 9, 1953 E dd iA-fi? THREAD BREAK DETEGTGR .l'ohn Wesley Harvey, .liu, Richmond, Va, assignor to E. 1. du Pont de Nemours and Company, Wilmington, Deb, a corporation of Delaware Filed May 16, 1962, Ser. No. 195,178 7 Claims. (ill. 57-81) This invention relates generally to new and useful im provements in devices for detecting yarn or thread breaks in textile yarn processing apparatus and, as illustrated herein, relates more particularly to an improved electrical switch actuating device of wide utility in the textile industry but especially useful under conditions of low yarn tension, as for example with textile downtwister machines.

Various devices for detecting yarn or thread breaks, with corresponding signalling or stop motion devices, are well known in the prior art. In processing yarn or thread from one textile machine position to another, it has been found highly desirable to quickly ascertain the presence of a break or serious loss of tension in the running yarn or thread. Such ascertainment, or detection has been accomplished by various means and forms of complex detecting mechanisms. Generally, these detecting devices contain mechanical or electrical means for actuating a machine stop motion device or signalling the need of corrective action. The single thread contacting elements of many of these devices have been of the gravity operated drop-wire type, and there have been those of the adjustable fly-wire type where the fly-wire is operated by spring tension.

While such prior art devices generally have operated fairly satisfactorily, they have not provided satisfactory detecting means that, in and of itself, imposes very little tension on a yarn which itself is under little tension in moving from one textile machine position to another. Also, such prior art devices are not desirable for use in certain arrangements for the plying together of several yarns into a single thread such as is performed on a downtwister machine. The imposition of appreciable variation in tension on the yarns by conventional drop-wire deviws results in the formation of undesirable loops in the twisted thread. This frequently can be caused by momentary retardation and appreciable tensioning of at least one yarn line at its unwind package which is caused by a. slight imperfection in the winding of the particular unwind package. The effect of this variation in tension can cause erratic movement of a single yarn sensing element and imposition of additional tension on the yarn line which are undesirable results.

It is an object of this invention to provide an improved yarn or thread break detector that will impose very little tension on yarns being plied together, thus preventing undesirable loops later on in the twisted thread.

Another object of this invention is to provide this device in such form that it will be useful wherever it is desirable to impose very little tension on a yarn when detecting yarn breaks.

A further objective of this invention is to provide this device with adjustment means for predetermining and concurrently controlling, in variable manner, the amount of tension imposed by the thread break detector upon the yarn or yarns, thus providing refinement of the detecting function.

Yet another object of this invention is the provision of an improved yarn break detector in which the yarn is engaged at two longitudinally spaced positions in a manner so that yarn tension and variations in yarn tension at these positions tend to act in opposition to each other to substantially cancel each other out in a differential action as far as operation of the detector device is concerned, and to avoid erratic operation of the detector and the imposition of additional tension to the yarn due to such erratic operation.

Further objectives of this invention are to provide this novel device in a relatively simple economical yet reliable form which performs effectively to handle the problems of initial tensioning, centrifugal forces, changed thread weights, engaging tension, variable multiplicity of yarn lines, thread deflection, oscillation of sensing means, speed of response, and others.

The objects of the invention are accomplished by the improved thread break detector of this invention which is comprised generally of a slightly unbalanced pair of counterbalanced thread-engaging detection means mounted on a pivotal member, an electrical switch means actuated by the detection means, these components and cooperating structure constructed and arranged to limit tension applied by the detection means to the engaged thread solely to the ditference in opposing torques applied by the slightly unbalanced detection means.

Other objects and advantages will appear from a consideration of the following specification, claims, and accompanying drawing in which:

FIGURE 1 is a side elevational view of the supporting structures (partly in section) with stationary thread guides mounted thereon, the improved thread break detector unit, and a thread line engaged therewith and FIGURE 2 is an extended cross-sectional view taken along line 2-2 of FIGURE 1 showing an aligned group of seven detection devices on units.

Referring now to the drawing in which like characters of reference designate similar parts in the respective views, FIGURE 1 shows the position of the thread break detector component parts with respect to a running thread line 40 with the thread break detector device in its locked or string up position. In the drawing the supporting structure of the thread break detector comprises two metal angle frame pieces 21 mounted on two L-beam structures 39 by means of four sets of clamp shoes 19 and socket head cap screws 20 with lockwashers. Bracing pieces 22 are welded to the steel angle frame pieces 21 to provide bracing therefor. Stationary thread guides 4 are mounted on the L-beam structures 39 by means of eyelet straps 41. A pair of outer supporting members 17 are adjustably mounted on the metal angle frame pieces 21 by means of socket head cap screws 23 with corresponding nuts and lockwashers. A pivot bar 10 is secured in bushings mounted in a pair of steel bosses 30 mounted in outer supporting members 17. The supporting structure is electrically grounded by a ground line to the pivot bar 10 or to screw 16 mounted in the outer supporting member 17.

The detection means of the thread break detector device comprises beam member 1 pivotally mounted by means of bearing elements 3 (shown in FIGURE 2) on the pivot bar 10. Thread guiding members 121 and 122 mounted in eyelet straps 24 are attached to opposite extremities of the beam member 1 by rivets 25 generally adjacent stationary thread guides 4. Adjustable weights 5 are slide ably mounted on the upper arms of the beam members opposed extremities for varying the sensing force applied to an engaged yarn line.

The electrical switch means which is actuated by the thread break detector device comprises a first rod memher 7 mounted in the outer supporting members 17 by means of a pair of electrically insulated bushings 12 compressively fitted around the first rod member 7 by means of socket head set screws 34 in threaded engagement with shoulder members 35 welded on the outer supporting members 17. The screws 3'4 are provided at each end of the first rod member 7 for adjusting the angular position of rod member 7. An elongated contact element 6 is adjustably mounted on the first rod member 7 by means ass aces of screws 11. The contacting element 6 is located slightly below the lower surface of one extremity of beam member '1, the contact element 6 is electrically connected to the high voltage side of a suitable relay system by means of a voltage line connected at one of screws 11. Obviously this element may be grounded and the other portions of the structure suitably connected to a high voltage source.

The locking means which facilitates initial string up is comprised of a spring-urged second rod member 13 movably mounted in the outer supporting members 17 by means of a pair of bearings 33. A lever-arm assembly consisting of a contact collar 29 and arm 14 locked in the contact collar 29 by screw 36 is attached to one end of the second rod member 13 by means of screw 37. Tension spring 8 which is under tension in the locked condition of the thread break detector is mounted at one of its two ends in a hole drilled in the second rod member 13 and at its other end by shoulder screw 38 mounted in one of the outer supporting members 17 A resilient limit-stop means for the pivoted member 1 comprises a pair of pivot arms 27 pivotally mounted on the outer supporting members 17 by means of shoulder screws 26; and, limited as to descending movement by adjusting screws 32 with corresponding lockwashers, and limited as to upward movement by tension spring 23.

Stop bar 9 is mounted at both of its ends in pivot arms 27 by means of screws, and is urged in the clockwise direction as shown in FIGURE 1 by tension spring 28. The other end of spring 23 is attached to screw 15 in one of the outer supporting members 17.

In the preferred embodiment of the improved thread break detector of this invention, multiple beam members 1 are used as shown in FIGURE 2. In such embodiment, plural electrical insulating pieces 18 consisting of essentially C-shaped pieces of polyethylene or other good electrical insulation or material are siideably fitted around the contacting element 6, and are movable or slideable along the length of the contacting element 6.

In the operation of the described thread break detector starting'with the initial threading of the device, the pivotedbeam member 1 is slightly unbalanced by positioning of the weights toward its portion of member it under which the contacting element 6 is positioned. The degree of unbalance between the beam members opposing extremities will determine the thread tension sensing force to be imposed on the running thread line 49' by thread guiding member 122. The member 122 will apply the sensing force due to the unbalanced Weight downward upon the running thread line 46, and the other member 121 will apply a force upward on the running thread line. It will be seen in FIGURE 1 that the configuration of beam member 1 is such that guides 121 and 122 are displaced laterally from the straight line connecting the guides 4. This causes the running yarn line to bear against the top of guides 1121 and 122, and results in imposition of a slight tension in the yarn line and opposing forces F and F on member 1 exerted at members 121 and 122. These forces are substantially balanced in the operating position or" the member 1 so that variations in the tension of the yarn line from causes other than the unbalanced sensing force essentially do not cause false signalling during operation or disturb the position of member ll. However, upon breakage of the yarn the sensing force due to the unbalanced weights will cause the member 1 to move into contact with contact element 6 to signal the break and/ or shut off the yarn handling apparatus with which the detector device is connected. In order to string up the device the beam member is locked in a generally horizontal position by rotating the spring-urged second rod member 13 by rotating arm 14 counterclockwise (as viewed in FIGURE 1), to position the second rod member 1?) against a lower surface section of the beam member 1. The rod member 13 is held in this position by means of tension spring 8. The stop bar 9 and rod member 13 thus serve to limit movement of the beam member 1 during string up and initial tensioning of the yarn.

The thread line 49, which is to be processed on a succeeding machine, is sequentially passed through a first stationary thread guide 4, the thread guiding member 123i mounted on the first portion of the beam member 1, the thread guiding member 122 mounted on the second portion of the beam member 1, the second stationary thread guide 4, and on to the succeeding machine (such as a textile downtwister) for further processing. After the threading operation is completed, the locking means is released by rotating the second rod member 13 downwardly out of contact With the bottom surface of the beam member 1. The member 122 of the beam member 1 is then free to engage the running thread line 40 under the influence of the unbalanced weight and to be supported thereby until such time as there is a break or significant loss of tension in the running thread line. Adjusting screws 23 are provided to vertically adjust the entire thread break detector so as to vary the tension imposed on the yarn line and magnitude of the balanced forces on members 12 1 and 122 and also to counteract any tendency by the beam member 1 to vibrate during operation of the thread break detector.

If a break in the running thread line 48 should occur, the member 122 of the beam member 1 descends until physical metal-to-metal contact is made between the lower edge of member 1 and contacting element 6. Since, as previously described herein, the beam member 1 is electrically grounded and the contacting element 6 is connected to the high voltage side of a suitable relay system or stop motion device; the electrical contacting of the beam member 1 and the contacting element 6 actuates the alarm or stopsthe thread processing device. The electrical system may include a time delay mechanism to preclude actuation of the relay system due to momentary, accidental contact by the beam member 1 with the contacting element 6.

The adjustable resilient limit-stop means provided in the thread break detector device reduces undesirable oscillation of he beam member 1 which occurs at times when the apparatus is started up.

In the preferred use of his thread break detector, which is in combination with a textile downtwister machine, a plurality of detection devices are employed as shown in FIGURE 2. In such preferred use it has been found desirable to provide a plurality of electrical insulating pieces 18 to insulate one or more of the beam members 1 in a given bank of detection devices from the contacting element 6 when said beam member (or members) is not being used to engage a running thread line. When any beam member 1 is to be inactivated, an insulating piece 18 is slideably positioned under the beam member to be inactivated, thus permitting normal operation of the remaining activated detection means.

The thread break detector of this invention is particularly useful where the imposition of considerable tension on the yarn by the detector is undesirable. It has been found particularly useful in the plying together of several strands of synthetic yarn to form a single thread. Conventional drop-wire devices have caused loops in the final thread due to over-stretching of at least one strand of the yarn when an imperfection in at least one yarn package caused a momentary increase in tension. The detector of this invention may be used in any application Where a sensitive thread break detector is desired. The instantaneous tension imposed from sources external to the detector device on the running thread line may be varied within limits without aiiecting the operation of the device. Appropriate adjustments of the adjustable weights on the beam members first and second portions very accurately control the sensing force.

It can be seen that applicant has provided a novel improved thread break detector. Various modifications within the spirit of this invention will occur to those skilled in the art and it is intended that all .such are to be included within the scope of the following claims.

I claim:

1. An improved thread break detector comprising, in combination, a supporting structure, an unbalanced first means pivotally mounted on said supporting structure adapted to engage a tensioned thread at two longitudinally spaced opposed positions along said tensioned thread, a second means mounted on said structure and positioned to engage a first portion of an overbalanced extremity of said first means upon movement of said first means responsive to a significant drop in tension of said tensioned thread, said first and second means being further constructed and arranged to have an electrical voltage differential maintained therebetween while said first means overbalanced extremity is supported by tension in said thread, a third means movably mounted in the supporting structure for locking the first means in a given position during initial engagement by said first means with said tensioned thread, and a fourth pivotal means adjustably mounted in the supporting structure for resiliently limiting said first means movement in one direction.

2. The device of claim 1 in which said unbalanced first means comprises a sensing member having two opposed unbalanced extremities constructed and arranged to exert a very small magnitude sensing force by said overbalanced extremity on the tensioned thread proportional to the degree of unbalance between extremities, and to substantially isolate the member from the action of sudden increases in thread tension and cause engagement of said overbalanced extremity and said second means only in response to drops in thread tension below a given predetermined minimum value.

3. An improved thread break detector comprising, in combination, a supporting structure, a detection means electrically grounded and pivotally mounted on the supporting structure with an underbalanced first portion and an opposed overbalanced second portion both portions constructed and arranged to contact a tensioned thread in opposed engagement, an electrically insulated assembly adapted to be connected to a source of high voltage and mounted in the supporting structure and positioned to engage said grounded detection means upon movement of said detection means in response to significant drop in tension of said tensioned thread, a locking means movably mounted in said supporting structure in cooperation with said detection means to prevent engagement of the assembly by the detection means during initial tensioning of said tensioned thread, and a resilient limit-stop means adjustably mounted in said supporting structure in cooperation with said detection means and said locking means for limiting movement of said detection means When said locking means is actuated.

4. The device of claim 3 in which said detection means comprises a beam member pivotally mounted on said supporting structure, said beam member having a first portion and a second portion each constructed and arranged to contact a tensioned thread in opposed engagement, a plurality of adjustable weights of which at least one is slideably mounted on the beam member so as to overbalance said second portion, and two thread guiding members mounted on the beam member each near the extremity of said first and said second portions and adapted to contact a tensioned thread in opposed engagement.

5. The device of claim 4 in which said electrically insulated assembly comprises a first rod member mounted in the supporting structure and electrically insulated therefrom by a pair of non-conducting bushings, and a contacting element adjustably mounted on the first rod member and positioned to engage a first surface section of said beam members second portion when said tensioned thread loses tension to convert said loss of tension to actuation of an electrical circuit.

6. The device of claim 5 in which said locking means comprises a spring-loaded second rod member movably mounted in the supporting structure and adapted to cooperate with a second surface section of said beam members second portion, and a lever-arm assembly mounted on a first extremity of said second rod member and constructed and arranged to move the second rod member in-- to engagement against the beam member during initial tensioning of said tensioned thread and then remove said second rod member from engagement With the beam member to permit the beam members second portion to operatively engage the tensioned thread.

7. An improved thread break detector for a textile downtwister machine comprising, in combination, a supporting structure, a plurality of detection means electrically grounded and pivotally mounted on the supporting structure with each detection means having an underbalanced first portion and an overbalanced second portion both constructed to contact generally parallel tensioned threads in opposed engagement, an electrically insulated assembly mounted in the supporting structure and positioned to engage a surface section of each of said plural detection means overbalanced second portions in the event a tensioned thread engaged with one of said detection means loses tension to converting said loss of thread tension to actuation of an electrical circuit, a locking means movably mounted in said supporting structure in cooperation with each of said plural detection means to prevent engagement by any one of the plural detection means with said actuating assembly during initial tensioning of said tensioned threads, a resilient limit-stop means adjustably mounted in said supporting structure in cooperation with said plural detection means and said lock ing means for positively limiting movement of said plural detection means when said locking means is actuated, plural electrical insulating pieces slideably mounted on the actuating assembly and adapted to be so movably positioned as to selectively prevent actuation of said electrical circuit by one or more predetermined detection means.

References Cited in the file of this patent FOREIGN PATENTS 886,525 Great Britain Jan. 10, 1962 

1. AN IMPROVED THREAD BREAK DETECTOR COMPRISING, IN COMBINATION, A SUPPORTING STRUCTURE, AN UNBALANCED FIRST MEANS PIVOTALLY MOUNTED ON SAID SUPPORTING STRUCTURE ADAPTED TO ENGAGE A TENSIONED THREAD AT TWO LONGITUDINALLY SPACED OPPOSED POSITIONS ALONG SAID TENSIONED THREAD, A SECOND MEANS MOUNTED ON SAID STRUCTURE AND POSITIONED TO ENGAGE A FIRST PORTION OF AN OVERBALANCED EXTREMITY OF SAID FIRST MEANS UPON MOVEMENT OF SAID FIRST MEANS RESPONSIVE TO A SIGNIFICANT DROP IN TENSION OF SAID TENSIONED THREAD, SAID FIRST AND SECOND MEANS BEING FURTHER CONSTRUCTED AND ARRANGED TO HAVE AN ELECTRICAL VOLTAGE DIFFERENTIAL MAINTAINED THEREBETWEEN WHILE SAID FIRST MEANS'' OVERBALANCED EXTREMITY IS SUPPORTED BY TENSION IN SAID THREAD, A THIRD MEANS MOVABLY MOUNTED IN THE SUPPORTING STRUCTURE FOR LOCKING THE FIRST MEANS IN A GIVEN POSITION DURING INITIAL ENGAGEMENT BY SAID FIRST MEANS WITH SAID TENSIONED THREAD, AND A FOURTH PIVOTAL MEANS ADJUSTABLY MOUNTED IN THE SUPPORTING STRUCTURE FOR RESILIENTLY LIMITING SAID FIRST MEANS'' MOVEMENT IN ONE DIRECTION. 